Vehicle headlamp

ABSTRACT

A vehicle headlamp is provided with an upper stage light source unit, a middle stage light source unit, and a lower stage light source unit. The upper stage light source unit, the middle stage light source unit, and the lower stage light source unit are provided at a lamp body constituting a lamp member by way of a support member. A low beam light distribution pattern is formed on a front side of a vehicle by overlapping light from the respective light source units. The lower stage light source unit includes two subunits, the two subunits commonly share a single cylindrical lens.

This application claims foreign priority from Japanese PatentApplication No. 2006-030466, filed on Feb. 8, 2006, the entire contentsof which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle headlamp, particularlyrelates to a vehicle headlamp for forming a predetermined lightdistribution pattern by overlapping light emitted from a plurality oflight sources.

2. Related Art

In a background art, as a vehicle headlamp (headlamp), it is general touse a halogen bulb or a discharge bulb as a light source and reflectlight emitted from the light source to a front side by using a reflectoror a projecting lens. Although a halogen bulb or a discharge bulb is alight source capable of ensuring a sufficient light amount for vehicularuse, a problem that power consumption is large is posed.

On the other hand, there is a high tendency of adopting a semiconductorlight emitting element such as a light emitting diode as a light sourcefor a vehicle headlamp. A light emitting diode is generally small-sizedand power consumption thereof is small. Therefore, it is expected torealize to effectively use limited power by being applied to a vehiclemounted with a battery such as an automobile.

Although high luminance formation of a light emitting diode has beenpromoted, in comparison with a halogen bulb or a discharge bulb, aluminance thereof is not sufficient yet, and a light amount capable ofsufficiently ensuring optical recognizability cannot be irradiated to afront side by simply replacing a halogen bulb or a discharge bulb by alight emitting diode. Therefore, currently, it is general to conceivesuch that a plurality of light source units respectively including lightemitting diodes is mounted to a vehicle and a desired light distributionpattern is formed by over lapping light emitted from the light sourceunits.

For example, JP-A-2004-095480 discloses a vehicle headlamp for forming asynthesized light distribution pattern for low beam by combining threepieces of units for forming a cutoff line, five pieces of units forforming a hot zone, three pieces of units for forming a divergingregion. According to the vehicle headlamp, semiconductor light emittingelements are used in all of the units as the light sources, and thevehicle headlamp is constituted to form a light distribution pattern forlow beam having a pertinent light amount by overlapping lightdistribution patterns formed by respectives thereof.

Further, JP-A-2005-141918 discloses a vehicle headlamp for forming amain light distribution by using a projector type light source unitusing a discharge bulb, and using an additional light source unit usinga semiconductor light emitting element, capable of being switched on andoff and capable of being swiveled in a left and right direction andforming a synthesized light distribution pattern by overlapping andauxiliary light distribution on the main light distribution. Accordingto the vehicle headlamp, for example, by switching on the additionallight source unit in turning a vehicle and forming the additional lightdistribution pattern in a direction in accordance with a turningdirection, side optical recognizability of a vehicle, particularly,optical recognizability in the turning direction can be promoted.

Meanwhile, when a synthesized light distribution pattern is intended toprovide by combining a plurality of units as in JP-A-2004-095480, anumber of the units is necessarily increased, a number of parts isincreased and assembling performance is deteriorated in accordancetherewith. Further, the constitution is not preferable in view of cost.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a vehicleheadlamp capable of achieving excellent assembling performance byreducing a number of parts.

The invention is achieved by the following constitution.

(1) A vehicle headlamp provided with:

a plurality of light source units; and

a lamp member for supporting the plurality of light source units;

wherein a low beam light distribution pattern is formed on a front sideof a vehicle by overlapping light from the respective light sourceunits;

wherein one of the plurality of the light source units includes:

a lens having a focal line extended in a horizontal direction andextended substantially along a direction of the focal line; and

a first subunit and a second subunit for making light incident on thelens;

wherein the first subunit is a directly emitted type subunit having afirst light emitting element for emitting light from a vicinity of thefocal line of the lens in a direction of the lens for irradiating lightto the front side by way of the lens; and

wherein the second subunit is a reflecting type subunit including asecond light emitting element for emitting light, and a reflector forreflecting light from the second light emitting element to a vicinity ofthe focal line of the lens for irradiating light to the front side byway of the lens.

(2) The vehicle headlamp according to (1), wherein a light distributionpattern projected from the second subunit to the front side by way ofthe lens is diverged in a vertical direction more than a lightdistribution pattern projected from the first subunit to the front sideby way of the lens.

(3) The vehicle headlamp according to (1) or (2), wherein the firstlight emitting element and the second light emitting element arearranged on the same board.

(4) The vehicle headlamp according to any one of (1) through (3),wherein the first light emitting element is arranged at a vicinity ofthe focal line of the lens and above the focal line.

According to the one or more embodiments of the invention, one of theplurality of light source units includes the lens having the focal lineextended in the horizontal direction, and the first subunit and thesecond subunit for making light incident on the lens. The first subunitis the directly emitted type subunit having the first light emittingelement for emitting light from the vicinity of the focal line of thelens in the direction of the lens for irradiating light to the frontside by way of the lens. Further, the second subunit is the reflectingtype subunit having the second light emitting element for emitting lightand the reflector for reflecting light from the second light emittingelement to the vicinity of the focal line of the lens for irradiatinglight to the front side by way of the lens.

That is, according to the invention, the first subunit and the secondsubunit commonly share the single lens and therefore, in comparison witha case of providing respectively separate lenses, a number of parts canbe reduced and also spaces of attaching other attaching members of alens holder and the like can be made common. Therefore, the firstsubunit and the second subunit can be arranged proximately to eachother. Therefore, a space occupied by a total of the light source unitcan be reduced and the light source unit can be downsized.

Further, according to the invention, as “the lens having the focal lineextended in the horizontal direction”, for example, a cylindrical lens,a toroidal lens or the like can be pointed out. Here, the toroidal lensis a lens having a shape substantially similar to a shape of a surfaceof a doughnut and is a lens which is provided with a focal linesubstantially in a circular arc shape and in which radii of curvature ofa contour line of a section orthogonal to the focal line and is acontour line of a section in parallel with the focal line differ fromeach other. The cylindrical lens is a lens having a shape of acylindrical shape by making the radius of curvature of the contour lineof the section in parallel with the focal line infinitive, that is,constituting the contour line by a linear line in the toroidal lens.

Further, according to the embodiments, the light distribution regionprojected from the second subunit to the front side by way of the lensis diverged in the vertical direction more than the light distributionpattern projected from the first subunit to the front side by way of thelens. This is mainly owing to the difference between the directlyemitted type and the reflecting type and various light distributionpatterns can be realized even when the single lens is used.

Further, according to the embodiments, the two light emitting elementsare arranged on the same board. Therefore, in assembling, the two lightemitting elements may be positioned to the single board and may becombined with other member and therefore, assembling performance can bepromoted and accuracies of positioning the two light emitting portionscan also be promoted by constituting a reference by the single board.

Further, the first light emitting element of the first subunit isarranged at the vicinity of the focal line of the lens and above thefocal line. Therefore, light projected to the front side to the frontside by way of the lens can be provided with a cutoff line and, forexample, a diverging region constituting a portion of a horizontal lineat a vicinity of H line needing a clear brightness boundary can beformed.

Other aspects and advantages of the invention will be apparent from thefollowing description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing a vehicle headlamp according to anembodiment of the invention.

FIG. 2 is a sectional view taken along a line II-II of the vehicleheadlamp according to the embodiment.

FIG. 3 is a vertical sectional view of a first subunit (second subunit)provided at an upper stage light source unit.

FIG. 4 is a vertical sectional view of a third subunit provided at amiddle stage light source unit.

FIGS. 5( a) and 5(b) illustrate horizontal sectional views of the thirdsubunit (fourth subunit).

FIG. 6 is a perspective view of a lower stage light source unit.

FIG. 7 is a vertical sectional view showing a fifth subunit of the lowerstage light source unit.

FIG. 8 is a vertical sectional view showing a sixth subunit of the lowerstage light source unit.

FIG. 9 is a top view of the lower stage light source unit.

FIG. 10 is a view showing a light distribution pattern for low beamformed by the vehicle headlamp of the embodiment.

FIG. 11 is a view showing a light distribution pattern for high beamformed by the vehicle headlamp of the embodiment.

FIGS. 12( a) to 12(d) illustrate schematic sectional views showing arelationship between the third subunit and a light distribution pattern.

FIGS. 13( a) to 13(d) illustrate other schematic sectional views showingthe relationship between the third subunit and the light distributionpattern.

FIGS. 14( a) to 14(h) illustrate views showing a relationship betweenpivoting movement and a light distribution pattern when a divergingmember is provided at a light source unit of a directly emitted type.

FIG. 15 is a control block diagram showing a control related to thevehicle headlamp of the embodiment and switching ON/OFF thereof.

FIG. 16 is a table showing a pattern of controlling to switch ON/OFF bya switch ON/OFF controller.

FIGS. 17( a) to 17(d) illustrate schematic views showing examples ofrealizing light distribution patterns in AFS.

FIGS. 18( a) to 18(c) illustrate schematic views showing examples ofrealizing light distribution patterns in AFS.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

An explanation will be given of exemplary embodiments of a vehicleheadlamp according to the invention in reference to the drawings asfollows.

FIG. 1 is a front view showing a vehicle headlamp according to theembodiment of the invention. FIG. 2 is a sectional view taken along aline II-II of the vehicle headlamp. FIG. 3 is a vertical sectional viewof a first subunit provided at an upper stage light source unit. FIG. 4is a vertical sectional view of a third subunit provided at a middlestage light source unit. FIGS. 5( a) and 5(b) illustrate horizontalsectional views of the third subunit. FIG. 6 is a perspective view of alower stage light source unit. FIG. 7 is a vertical sectional viewshowing a fifth subunit of the lower stage light source unit. FIG. 8 isa vertical sectional view showing a sixth subunit of the lower stagelight source unit. FIG. 9 is a top view of the lower stage light sourceunit.

A vehicle headlamp 10 according to the embodiment is a headlamp attachedto, for example, a front end portion of a vehicle, and capable of beingswitched on and off by selectively switching low beam and high beam. InFIG. 1, as an example, a headlamp unit (headlamp unit) attached to aright front side of a vehicle of an automobile or the like is shown asthe vehicle headlamp 10.

As shown by FIG. 1 and FIG. 2, the vehicle head lamp 10 includes a lighttransmitting transparent cover 12 and a lamp body (lamp member) 14.Further, three of light source units (an upper stage light source unit20, a middle stage light source unit 40, a lower stage light source unit60) are fixedly arranged above a support member 15 at inside of a lampchamber 10 a surrounded by the transparent cover 12 and the lamp body14. Further, an extension 16 is arranged between the three light sourceunits 20, 40, 60 and the transparent cover 12 to cover a gap when viewedfrom a front side of a lamp piece.

The support member 15 includes three installing portions 15 a, 15 b, 15c having different heights, which are respectively arranged fixedly withthe upper stage light source unit 20, the middle stage light source unit40, the lower stage light source unit 60 in this order. The supportmember 15 is fixed to the lamp body 14 by way of a support mechanism 17inclinable by way of an inclining shaft 17 a substantially in parallelwith a width direction of a vehicle, and a power transmitting shaft 18 bconnected to a drive shaft 18 a of a motor 18 for leveling constitutingan actuator. The support mechanism 17, the motor 18 for leveling and thepower transmitting shaft 18 b constitute a leveling mechanism foradjusting an angle of attaching the support member 15 to the lamp body14 in accordance with an output of the motor 14 for leveling. Accordingto the embodiment, optical axes of the respective light source units 20,40, 60 can be adjusted by adjusting the angle of attaching the supportmember 15 by way of the leveling mechanism.

Next, the respective light source units 20, 40, 60 will be explained.

According to the embodiment, the respective light source units 20, 40,60 are light source units respectively having different roles inrespectively forming light distribution patterns and constituted torealize various light distribution patterns by selectively switching onand off the respective light source units 20, 40, 60.

First, the upper stage light source unit 20 will be explained asfollows.

The upper stage light source unit 20 is a light source unit for forminga light distribution for high beam and includes a pair of a first and asecond subunit 20A, 20B respectively having the same constitution asshown by FIG. 1. The first and the second subunits 20A, 20B areinstalled to align in a width direction at a topmost stage of theinstalling portion 15 a of the support member 15. Further, the first andthe second subunits 20A, 20B may be formed as the pair or may be formedseparately.

As shown by FIG. 3, the first subunit 20A (similar to the second subunit20B) includes a metal made base member 21 having substantially an L-likeshape in a sectional view thereof, LED (semiconductor light emittingelement) 22 as a light source, and a projecting lens 24.

The base member 21 is arranged on the installing portion 15 a of thesupport member 15 at a base member portion 21 a thereof extended in afront and rear direction of a vehicle, and LED 22 is fixedly arranged toa vehicle front side of an erected portion 21 b erected from theinstalling portion 15 a.

LED 22 is a white light emitting diode having a light emitting portion(light emitting chip) 22 a having a size of about 1 mm square and isarranged with a light emitting portion 22 a for emitting light in astate of being directed to a vehicle front face side.

The projecting lens 24 is an aspherical lens of a convex lens type forprojecting light emitted from the light emitting portion 22 a of LED 22to a vehicle front side and is fixed to the base member 21 at a vicinityof a vehicle front side front end portion 21 c of the base memberportion 21 a. According to the embodiment, a focal point P₂₄ of theprojecting lens 24 is constituted to substantially coincide with thelight emitting portion 22 a of LED 22. Therefore, light emitted from thelight emitting portion 22 a of LED 22 is directly incident on theprojecting lens 24 and incident light is projected to the front sidealong an optical axis Ax1 as substantially parallel light. That is, thefirst and the second subunits 20A, 20B of the light source unit 20 ofthe embodiment respectively constitute projector type light source unitsof a directly emitted type.

Next, the middle stage light source unit 40 will be explained.

The middle stage light source unit 40 is a light source unit for forminga portion of a light distribution for low beam, and includes a pair of athird and a fourth subunit 40A, 40B respectively having the sameconstitution as shown by FIG. 1. The third and the fourth subunits 40A,40B are installed to align in a width direction at a middle stage of theinstalling portion 15 b of the support member 15. Further, according tothe embodiment, the third and the fourth subunits 40A, 40B arerespectively formed by separate members.

As shown by FIG. 4, the third subunit 40A (similar to the fourth subunit40B) includes, for example, a base member 41 substantially in an L-likeshape, LED (semiconductor light emitting element) 42 as a light source,a projecting lens 44, a reflector 46.

The base member 41 includes a base member portion 41 a extended in thefront and rear direction of the vehicle, and an erected portion 41 b iserected from the base member portion 41 a, and an optical mountingportion 41 c for fixedly mounting LED 42 and the reflector 46 isextended by being folded from the erected portion 41 b to a rear side ofthe vehicle.

LED 42 is a white diode similar to LED 22 and is mounted on a mountingface 41 e of the mounting portion 41 c in a state of directing a lightemitting portion 42 a thereof substantially in a vertical upperdirection. Further, the light emitting portion 42 a may be constitutedto be arranged with more or less angle in accordance with a shape of thelight emitting portion or a light distribution irradiated to a frontside.

The reflector 46 is a reflecting member formed with a reflecting face 46a having a vertical sectional shape substantially in an elliptical shapeand having a horizontal sectional shape in a shape of a free curved facebased on an ellipse. The reflector 46 is designed and arranged such thata first focal point P₄₄₁ thereof is disposed at a vicinity of the lightemitting portion 42 a of LED 42 and a second focal point P₄₄₂ thereof isdisposed at a vicinity of a brow line 41 g made by the mounting face 41e of the mounting portion 41 c and a front face 41 f of the erectedportion 21 b.

Light emitted from the light emitting portion 22 a of LED 22 isreflected by the reflecting face 46 a of the reflector 46 and isincident on the projecting lens 44 by passing a vicinity of the secondfocal point P₄₄₂. Further, the third and the fourth subunits 40A, 40Bare constituted such that a skewed cutoff line is formed at a lightdistribution pattern projected to the front side of the vehicle byselectively cutting light by reflecting a portion of light by themounting face 41 e by constituting a boundary line by the brow line 41 gmade by the mounting face 41 e of the mounting portion 41 c and thefront face 41 f of the erected portion 21 b. That is, the brow line 41 gconstitutes a brightness boundary line of the third and the fourthsubunits 40A, 40B. Further, it is preferable that also a portion oflight reflected by the reflecting face 46 a of the reflector 46 andfurther reflected by the mounting face 41 e is irradiated to the frontside as effective light. Therefore, according to the embodiment, thevehicle front side of the mounting face 41 e is provided with an opticalshape in which an angle of reflection thereof is set pertinently inconsideration of a positional relationship between the projecting lens44 and the reflector 46.

The projecting lens 44 is an aspherical lens of a convex lens type forprojecting light reflected by the reflecting face 46 a of the reflector46 to the vehicle front side, and is fixed to the base member 41 at avicinity of the vehicle front side front end portion 41 c of the basemember portion 41 a. According to the embodiment, a focal point of theprojecting lens 44 is constituted to substantially coincide with thesecond focal point P₄₄₂ of the reflector 46. Therefore, light incidenton the projecting lens 44 by being reflected by the reflector 46 isprojected to the front side as substantially parallel light. That is,the third and the fourth subunits 40A, 40B of the light source unit 40of the embodiment respectively constitute projector type light sourceunits of a reflecting type for forming to cut converged light.

Further, according to the embodiment, the third and the fourth subunits40A, 40B are fixed to the support portion 15 d and the installingportion 15 b respectively pivotably by way of pivoting shafts 50 a, 50b. The pivoting shaft 50 b on one side is connected to an actuator 19,the third and the fourth subunits 40A, 40B are swiveled in a left andright direction respectively independently from each other byconstituting axes thereof by the pivoting shaft 50 a, 50 b by a driveforce of the actuator 19 to make directions of optical axes thereofvariable although a description will be given thereof later in details.That is, the third and the fourth subunits 40A, 40B respectivelyconstitute optical axes variable light source units capable of changingthe directions of the optical axes independently from other light sourceunit.

Specifically, the third and the fourth subunits 40A, 40B can changeoptical axes Ax2 such that an irradiating position in a horizontaldirection is changed as shown by FIG. 5( b) from a front face (state ofbeing directed in 0° direction) as shown by FIG. 5( a). Thereby, aposition of a light converging region can be changed between a center ofa front side of the vehicle and a side of the front side of the vehicle.Therefore, for example, a direction of the optical axis Ax2 is changedand light is irradiated to the side of the front side of the vehicle bybeing pivoted by constituting the axis by the pivoting shafts 50 a, 50 bin the horizontal direction in accordance with a side in a turningdirection in turning the vehicle or the like. Thereby, opticalrecognizability in a direction of advancing the vehicle can be promoted.

Further, according to the embodiment, a diverging ember 55 is providedat least on one side (left side in the drawing) of sides of a regionbetween the projecting lens 44 and the brown line 41 g, that is, betweenthe projecting lens 44 and the reflector 46. According to theembodiment, the diverging member 55 diverges light emitted from thelight source and reflected by the reflector 46 further in a sidedirection. The diverging member 55 may be arranged only on one side ormay be arranged on both sides. When arranged only on one side, it ispreferable to provide the diverging member on a side of arranging thevehicle headlamp 10 on the front side of the vehicle, that is, rightside when arranged on the right side of the vehicle, or left side whenarranged on the left side of the vehicle.

The diverging member 55 of the embodiment is a prism diverging lens inwhich a wall thickness thereof along the front and the rear direction ofthe vehicle, that is, a direction of propagating light is thickened asbeing remote from the optical axis Ax2. The diverging member 55 is fixedto the lamp body 14 or the support member 15 by way of a fixed member,not illustrated, at a position on which light is not incident when thethird and the fourth subunits 40A, 40B each is directed to the frontside (state of being directed in 0° direction). On the other hand, whenthe optical axis Ax2 is changed to change the irradiating position inthe horizontal direction as shown by FIG. 5( b), a portion of light isincident on the diverging member 15, and light is diverged in a sidedirection. Thereby, a light amount irradiated in the side direction isincreased and side optical recognizability can further be promoted.

Next, the lower stage light source unit 60 will be explained.

The lower stage light source unit 60 is a light source unit for forminga portion of the light distribution for low beam and includes two of afifth and a sixth subunit 70, 80 respectively having differentconstitutions, and one cylindrical lens 65. The fifth and the sixthsubunits 70, 80 are installed to align in a width direction at alowermost stage of the installing portion 15 c of the support member 15.

As shown by FIG. 6, the fifth and the sixth subunits 70, 80 include abase member 90 as a common base member. The fifth subunit 70 isconstituted by arranging LED 72 on the base member 90, and the sixthsubunit 80 is constituted by including LED 82 and a reflector 86 on thebase member 90. Further, the single cylindrical lens 65 is arranged onfront sides of the fifth and the sixth subunits 70, 80 in the front andrear direction of the vehicle. According to the embodiment, thecylindrical lens 65 is constituted as a projecting lens commonly sharedby the two subunits 70, 80.

According to the base member 90, as shown by FIG. 7, a base memberportion 90 a extended in the front and rear direction of the vehicle isarranged on the installing portion 15 c of the support member 15, and anerected portion 90 b is erected from the base member portion 90 a. Astepped difference portion 90 h is formed by cutting off a portion of anupper side of the erected portion 90 b, and LED 72 is mounted to avehicle front side of the stepped difference portion 90 h. According tothe embodiment, the fifth subunit 70 is constituted by LED 72.

LED 72 is a white diode similar to LED 22, and a light emitting portion72 a is fixedly arranged on the stepped difference portion 90 h in astate of being directed to the front side in the front and reardirection of the vehicle. Further, the light emitting portion 72 a maybe constituted to be arranged with more or less angle in accordance witha shape of the light emitting portion and the light distributionirradiated to the front side.

The cylindrical lens 65 is a lens having substantially a cylindricalshape for projecting light emitted from the light emitting portion 72 aof LED 62 to the front side of the vehicle and is fixed to the basemember 90 at a vicinity of a vehicle front side front end portion 90 cof the base member portion 90 a. The cylindrical lens 65 is providedwith a single piece of a focal line L₆₅ and is constituted such that thefocal line L₆₅ is disposed at a vicinity of a lower end of the lightemitting portion 72 a of LED 72 as shown by FIG. 7. Therefore, lightemitted from the light emitting portion 72 a of LED 72 is directlyincident on projecting lens 65 to project a light distribution patternincluding a cutoff line in correspondence with the focal line L₆₅ to thefront side along an optical axis Ax3 by constituting substantiallyparallel light by incident light. That is, the fifth subunit 70 of theembodiment constitutes a projector type light source unit of a directlyemitted type.

On one side in the width direction of the vehicle of the base member 90,a portion of the erected portion 90 e is folded to bend to a rear sideof the vehicle, a mounting portion 90 c for mounting to fix LED 82 andthe reflector 86 is extended, thereby, the sixth subunit 80 isintegrally formed contiguously to the fifth subunit 70.

LED 82 is a white diode similar to LED 22, and a light emitting portion82 a thereof is mounted on a mounting face 90 e of the mounting portion90 c in a state of being directed substantially in a vertical upperdirection. Further, the light emitting portion 82 a may be constitutedto arrange with more or less angle in accordance with a shape of thelight emitting portion and a light distribution pattern irradiated tothe front side.

The reflector 86 is a reflecting member formed with a reflecting face 86a having a vertical sectional shape substantially in an elliptical shapeand a horizontal sectional shape in a free curved face constituting areference by an ellipse on an inner side thereof. The reflector 86 isdesigned and arranged such that a first focal point P₈₆₁ thereof isdisposed at a vicinity of a light emitting portion 82 a of LED 82, and asecond focal point is disposed at a vicinity of a brow line 90 g made bythe mounting face 90 e of the mounting portion 90 c and a front face 90f of the erected portion. According to the embodiment, a positionalrelationship with the cylindrical lens 65 is set such that a focal lineL₆₅ of the cylindrical lens 65 is arranged at a vicinity of the browline 90 g made by the mounting face 90 e of the mounting portion 90 cand the front face 90 f of the erected portion 90 b.

Therefore, light emitted from the light emitting portion 22 a of LED 22is reflected by the reflecting face 86 a of the reflector 86 and isincident on the cylindrical lens 65 by passing a vicinity of the focalline L₆₅. Light incident on the cylindrical lens 65 is projected to afront side along an optical axis Ax4 by constituting substantiallyparallel light in the vertical direction.

Further, the sixth subunit 80 is constituted to form a cutoff line in alight distribution pattern projected to the front side of the vehicle byselectively cutting light by reflecting a portion of light by themounting face 90 e by constituting a boundary line by the mounting face90 e of the mounting portion 90 c and the front face 90 f of the erectedportion 90 b. Further, it is preferable that also a portion of lightreflected by the reflecting face 86 a of the reflector 86 and furtherreflected by the mounting face 90 e is irradiated to the front side aseffective light. Therefore, according to the embodiment, the vehiclefront side of the mounting face 90 e is provided with an optical shapefor pertinently setting an angle of reflection in consideration of apositional relationship between the cylindrical lens 65 and thereflector 86.

On the other hand, as shown by FIG. 9, with regard to the widthdirection of the vehicle, light reflected by the reflecting face 86 a ofthe reflector 86 is incident on the cylindrical lens 65 in a state ofbeing diverged without particularly changing an advancing direction.Therefore, with regard to the width direction of the vehicle, lightemitted from the sixth subunit 80 becomes diverged light. In this way,the sixth subunit 80 of the embodiment constitutes a projector typelight source unit of a reflecting type.

In this way, according to the lower stage light source unit 60 of theembodiment, the fifth subunit 70 and the sixth subunit 80 commonly sharethe same cylindrical lens 65. Therefore, a number of parts can bereduced in comparison with that in the case of respectively providingthe lenses, also spaces of attaching the lens holder, other attachingmember and the like can be made to be common and therefore, the fifthsubunit 70 and the sixth subunit 80 can be arranged to be proximate toeach other. Therefore, the lower stage light source unit 60 can bedownsized by reducing a space occupied by a total of the lower stagelight source unit 60.

Next, an explanation will be given of a basic light distribution patternformed by the head lamp 10 of the embodiment in reference to FIG. 10 andFIG. 11. The vehicle headlamp 10 of the embodiment can form a lightdistribution pattern LP for low beam and a light distribution pattern HPfor high beam as basic light distribution patterns.

FIG. 10 is a diagram showing the light distribution pattern LP for lowbeam formed by the vehicle headlamp 10 of the embodiment.

The light distribution pattern LP for low beam is formed by switching onthe middle stage light source unit 40 and the lower stage light sourceunit 60.

Specifically, by switching on the third and fourth subunits 40 a, 40 bof the middle stage light source unit 40, light is irradiated to anarrow first region D1 at a vicinity of an intersection of H-V lines ona front side of a front face of the vehicle. The first region D1includes a cutoff line CL1 substantially in a Z-like shape formed incorrespondence with the blow lines 41 g formed at the third, the fourthsubunit 40 a, 40 b. Further, a region downward from the cutoff line CL1is set as a hot zone Hz having a high light amount in the first regionD1.

Further, by switching on the fifth, the sixth subunits 70, 80 of thelower stage light source unit 60, a second region D2 and a third regionD3 extended in a width direction of the vehicle (H line direction) areformed respectively downward from the first region D1.

The second region D2 formed by the fifth subunit 70 is formed at adownward vicinity of the first region D1 to partially overlap the firstregion D1. An upper end of the second region D2 is formed with a cutoffline CL2 formed by the fifth subunit 70. According to the embodiment,the cutoff line CL2 is set to be projected to the front side to becontinuous to the cutoff line CL1 of the first region D1.

Further, the third region D3 formed by the sixth subunit 80 is formeddownward from the second region D2 to partially overlap the secondregion D2. Since the sixth subunit 80 is the reflecting type projectorlight source unit, light is irradiated in a wide direction in thevertical direction more easily than the sixth subunit 70 constitutingthe directly emitted type projector light source unit. Therefore,according to the embodiment, there is constructed a constitution offorming the third region D3 as a short distance diverging region forpromoting short distance optical recognizability by the sixth subunit 80and forming the second region D2 as a long distance diverging region forpromoting long distance optical recognizability by the fifth subunit 70.

In this way, according to the embodiment, the light distribution patternLP for low beam is formed by combining the first region D1, the secondregion D2 and the third region D3 formed by the middle stage lightsource unit 40 and the lower stage light source unit 60.

FIG. 11 is a diagram showing the light distribution pattern HP for highbeam formed by the vehicle headlamp 10 of the embodiment.

The light distribution pattern HP for high beam is formed by switchingon the middle stage light source unit 40 and the lower stage lightsource unit 60 as well as the upper stage light source unit 20.

Specifically, there is constructed a constitution in which by switchingon the upper stage light source unit, a fourth region D4 is irradiatedoverlappingly on the first region D1, the second region D2 and the thirdregion D3 formed by the middle stage light source unit 40 and the lowerstage light source unit 60. The fourth region D4 is a light distributionpattern diverged in an up and down direction and in a left and rightdirection centering on a vicinity of an intersection of H-V lines.According to the light distribution pattern HP for high beam, a lightamount of a total is increased by forming the fourth region D4 tothereby promote remote optical recognizability.

Further, according to the embodiment, in forming the light distributionpattern HP for high beam, there is constructed a constitution of furtherpromoting remote optical recognizability by arranging the hot zone Hz ata vicinity in a horizontal direction 0° by respectively shifting theoptical axes Ax2 slightly (0.5 through 5°) in the right direction bypivoting the middle stage light source units 40 a, 40 b of the middlestage light source unit 40.

Next, an explanation will be given of a relationship between pivotingmovement of the third, the fourth subunits 40 a, 40 b of the middlestage light source unit 40 according to the embodiment and the lightdistribution pattern in reference to FIG. 12 and FIG. 13.

FIGS. 12( a) to 12(d) illustrate schematic sectional views showing arelationship between the third subunit 40 a and the light distributionpattern. Specifically, FIG. 12( a) is a schematic horizontal sectionalview when the third subunit 40 a (the same also in the case of thefourth subunit 40 b) is pivoted in a left direction by 15° in a case ofa constitution of not arranging the diverging member 55, and FIG. 12( b)is a schematic diagram showing the light distribution pattern. Further,FIG. 12( c) is a schematic horizontal sectional view when the thirdsubunit 40 a is pivoted in the left direction by 15° in a case of aconstitution of being arranged with the diverging member 55, and FIG.12( d) is a schematic diagram showing the light distribution pattern. InFIGS. 12( a) to 12(d), a prism diverging lens is used as the divergingmember 55.

As is known by comparing FIG. 12( a) and FIG. 12( c), when the divergingmember 55 is arranged, in a state of pivoting the third subunit 40 a, aportion of light is incident on the diverging member 55 immediatelybefore being incident on the projecting lens 44 and a direction ofadvancing light is bent to a pivoting side. Therefore, light emittedfrom the projecting lens 44 is diverged more in a side direction whenthe diverging member 55 is arranged.

When the specific light distribution patterns are compared, whereas inthe light distribution pattern D11 shown in FIG. 12( b), a rise positionof the cutoff line is inclined by 15° the same as the pivoting angle, inthe light distribution pattern D12 shown in FIG. 12( d), a rise positionof the cut offline is inclined by 20° larger than the pivoting angle by5°. This is because light is diverged in the side direction by thediverging member 55. As a result, it is known that a total of the lightdistribution pattern is diverged to extend in the vehicle widthdirection.

FIGS. 13( a) to 13(d) illustrate other schematic sectional views showingthe relationship between the third subunit 40 a and the lightdistribution pattern.

Specifically, FIG. 13( a) is a schematic horizontal sectional view whenthe third subunit 40 a is pivoted in the left direction by 20° in a caseof a constitution of not arranging the diverging member 55, and FIG. 13(b) is a schematic diagram showing the light distribution pattern.Further, FIG. 13( c) is a schematic horizontal sectional view when thesubunit 40 a is pivoted in the left direction by 20° in a case of aconstitution of arranging the diverging member 55, and FIG. 13( d) is aschematic diagram showing the light distribution pattern. In FIGS. 13(a) to 13(d), there is used a step diverging lens formed with a pluralityof cylindrical steps 55 a on the reflector side as the diverging member53.

As is known by comparing FIG. 13( a) and FIG. 13( c), when the divergingmember 55 is arranged, in a state of pivoting the third subunit 40 a, aportion of light is incident on the diverging member 55 immediatelybefore being incident on the projecting lens 44 and a direction ofadvancing light is bent to the pivoting side. Therefore, light emittedfrom the projecting lens 44 is more diverged in the side direction whenthe diverging member 55 is arranged. Further, when the step diverginglens is used as the diverging member 55, a portion of light is bent alsoin a direction reverse to the pivoting side, as a result, light isdiverged in both of left and right directions.

When the specific light distribution patterns are compared, whereasaccording to a light distribution pattern D13 shown in FIG. 13( b), arise position of the cutoff line is inclined by 20° the same as thepivoting angle, according to a light distribution pattern D14 shown inFIG. 13( d), a rise position of the cutoff line is inclined by 15°smaller than the pivoting angle by 5°. Further, as shown by FIG. 13( d),a region of the light distribution pattern D14 is extended considerablyto left side by about 35°. This is because light is diverged both inleft and right directions by the diverging member 55. As a result, it isknown that a total of the light distribution pattern is diverged toextend in the vehicle width direction.

In this way, when the diverging member 55 is arranged, light is divergedand therefore, the light distribution pattern can be shifted in the sidedirection by the pivoting angle or more. Therefore, even in a case of anarrangement restricting amounts of pivoting the third, the fourthsubunits 40 a, 40 b, the diverging member 55 can diverged to irradiatelight in the side direction by the pivoting angle or more. Conversely,the pivoting amount can be made to be small in comparison with an amountof shifting the light distribution pattern and therefore, the total ofthe light source unit can be made to be compact by reducing a space forpivoting. Further, since the pivoting amount is small, actuators fordriving the third, the fourth subunits 40 a, 40 b can also be downsized.

Further, although in the above-described explanation, there is shown aconstitution of attaching the diverging members 55 to the third, thefourth subunits 40 a, 40 b of the reflecting type, the invention is notlimited thereto but the middle stage light source unit 40 may beconstituted by respectively replacing the third, the fourth subunits 40a, 40 b by the light source units 40 c of the directly emitted type asshown by FIG. 14.

FIGS. 14( a) to 14(h) illustrate views showing a relationship betweenthe pivoting movement and the light distribution pattern when thediverging member is provided to the directly emitted type light source,FIGS. 14( a) and 14(b) are respectively views showing the light sourceunit and the light distribution pattern when the pivoting angle is 0°.FIGS. 14( c) and 14(d) are respectively views showing the light sourceunit and the light distribution pattern when the pivoting angle is 20°.FIGS. 14(e) and 14(f) are respectively views showing the light sourceunit and the light distribution pattern when the pivoting angle is 20°.FIGS. 14( g) and 14(h) are respectively views showing the light sourceunit and the light distribution pattern when the pivoting angle is 30°.

The light source unit 40 c of the directly emitting type is constructedby a constitution similar to that of the fifth subunit 70 shown in FIG.7 and is constructed by a constitution of arranging a light emittingportion 40 c of LED at a vicinity of a focal point of a projecting lens40 c. Even in the constitution, as shown by FIGS. 14( c) and 14(d), whena total of the unit is inclined by 10°, a total of the lightdistribution pattern is shifted in the side direction on the left sideby 100 and a length in the vehicle width direction (horizontaldirection) of the light distribution pattern is extended. The tendencyis increased further when the total of the unit is inclined by 20° asshown by FIGS. 14( e) and 14(f), further, it is known that as shown byFIGS. 14( g) and 14(h), when the total of the unit is inclined by about30° and the diverging member 55 is extended to a degree of crossing theoptical axis Ax, the light distribution pattern is extended not only tothe left side but also to the right side.

In this way, even in the directly emitted type light source unit, whenthe diverging member 55 is arranged, light is diverged and therefore,the light distribution pattern can be shifted in the side direction bythe pivoting angle or more. Therefore, even in an arrangement ofrestricting the pivoting amount of the light source unit, the divergingmember 55 can diverge to irradiate light in the side direction by thepivoting angle or more. Conversely, the pivoting angle can be reduced incomparison with the amount of shifting the light distribution patternand therefore, a total of the light source unit can be made to becompact by reducing the space for pivoting. Further, since the pivotingamount is small, the actuator for driving the light source unit can alsobe downsized.

Next, a detailed explanation will be given of switch ON/OFF of thevehicle headlamp 10 of the embodiment in reference to FIG. 15.

FIG. 15 is a control block diagram showing a control related to thevehicle headlamp 10 of the embodiment and switch ON/OFF thereof. Aswitch ON/OFF control of the vehicle headlamp 10 of the embodiment iscarried out by a switch ON/OFF controller 100, a steering angle sensor110, a vehicle speed sensor 120, a high/low switching switch 130, abrightness sensor 140, a rain sensor 150 and a vehicle height sensor 160for outputting various signals to the switch ON/OFF controller 100. Allof these are similarly mounted to a vehicle mounted with the vehicleheadlamp 10.

The switch ON/OFF controller 100 is a control center portion forcontrolling to switch ON/OFF, increase light and reduce light ofrespectives of the respective light source units 20, 40, 60 of thevehicle headlamp 10, controls respective pivoting angles of the thirdand the fourth subunits 40 a, 40 b with regard to the middle stag lightsource unit 40, and adjusts leveling by controlling the motor 14 forleveling based on outputs from the various sensors and the switchmentioned above. The switch ON/OFF controller 100 is constituted toautomatically produce a light distribution adapted to a runningsituation. That is, according to the embodiment, AFS (Adaptive Frontlighting System) is realized by using the vehicle headlamp 10.

Next, the sensors and the switches will be explained.

The steering angle sensor 110 is a sensor for detecting an angle ofturning a vehicle, and, for example, a steering sensor for detecting asteering operation or the like can be used therefor. By a detectedsignal of the steering sensor 110, it can be determined whether thevehicle advances straight.

The vehicle speed sensor 120 is a sensor for detecting a speed of thevehicle. By a detected signal of the vehicle speed sensor 120, the speedof the vehicle can be determined and it can be determined whether thevehicle is running on a general road or running on a motorway of anautomobile exclusive road or the like.

The high/low switching switch 130 is a switch for switching high beamand low beam and is switched in accordance with an operation of a driverof driving the vehicle.

The brightness sensor 140 is a sensor for detecting a brightness of asurrounding of the vehicle. For example, by using the brightness sensor,it can be determined whether the vehicle runs on a dark country road orthe like, or runs in a relatively bright urban area.

The rain sensor 150 is a sensor for detecting whether rain falls. By adetected signal of the sensor, it can be determined whether the vehicleruns under rainy weather.

The vehicle height sensor 160 constitutes a portion of means fordetecting a pitch angle of the vehicle. According to the embodiment, theswitch ON/OFF controller 100 carries out automatic leveling bycontrolling the motor 18 for leveling based on an output signaloutputted by the vehicle height sensor 160.

The switch ON/OFF controller 100 of the embodiment forms a lightdistribution in accordance with a situation by controlling to switchON/OFF upper stage light source unit 20 (the first subunit 20 a and thesecond subunit 20 b) forming a light distribution for high beam, themiddle light source unit 40 (the third subunits 40 a, 40 b) for formingto cut to converge light for low beam, the fifth subunit 70 of the lowerstage light source unit 60 for forming long distance diverging light,the six subunit 80 of the lower stage light source unit 60 for formingshort distance diverging light independently from each other based onthe outputs from the sensors.

FIG. 16 is a table showing a pattern of the switch ON/OFF control of theswitch ON/OFF controller 100.

First, when the high/low switching switch 130 is selected to low, theswitch ON/OFF controller 100 forms the low beam light distributionpattern shown in FIG. 10 by not switching on the upper stage lightsource unit 20 and switching on other light source units 40, 70, 80.

Further, when the high/low switching switch 130 is selected to high, theswitch ON/OFF controller 100 forms the high beam light distribution byoverlapping the light distribution pattern formed by the upper stagelight source unit 20 on the low beam light distribution pattern byfurther switching on the upper stage light source unit 20. At thisoccasion, the third subunit 40 a and the fourth subunit 40 b of themiddle light source unit 40 may be pivoted in the right direction tothereby shift the first region D1 formed by the middle stage lightsource unit 40 to a vicinity of an intersection of H-V lines as shown byFIG. 11. Further, at this occasion, the switch ON/OFF controller 100 mayincrease the light amount to the front side by increasing light emittingamounts of the light emitting portions 42 a of the respective subunits40 a, 40 b by increasing power supplied to the middle light source unit40.

Next, an explanation will be given of various modes of a variable frontlight distribution system (AFS) realized in a low beam lightdistribution in reference to FIGS. 17( a) to 17(d) and FIGS. 18( a) to18(c).

FIGS. 17( a) to 17(d) and FIGS. 18( a) to 18(c) illustrate schematicviews respectively showing examples of realizing light distributionpatterns for AFS.

First, a curve mode will be explained.

The switch ON/OFF controller 100 determines that the vehicle is going toa curve when, for example, the vehicle is at a predetermined speed and asteering angle is a predetermined value or more based on signals fromthe steering angle sensor 110 and the vehicle speed sensor 120 inswitching on low beam. In this case, the switch ON/OFF controller 100realizes a light distribution pattern based on the curve mode.

Specifically, in the curve mode, the switch ON/OFF controller 100 makesthe upper stage light source unit 20 stay to be switched OFF andswitches ON the other light source units 40, 70, 80 similar to the lowbeam light distribution constituting a base. At this occasion, theswitch ON/OFF controller 100 pivots the third and the fourth subunits 40a, 40 b of the middle stage light source unit 40 respectively in leftand right inverse directions by about 20°. Thereby, as shown by FIG. 17(a), the first region D1 which has been irradiated to a center is dividedinto two to respectively irradiate in left and right directions.Thereby, left and right optical recognizability in curving is promoted.Further, in the curve mode, the third and the fourth subunits 40 a, 40 bmay be constituted to be pivoted in the same direction, or pivotingangles of the third and the fourth subunits 40 a, 40 b may beconstituted to change in accordance with signals from the steering anglesensor 110 and the vehicle speed sensor 120.

Next, a town mode will be explained.

The switch ON/OFF controller 100 determines that the vehicle is runningin an urban area when, for example, the vehicle runs at a predeterminedspeed or lower in a region having a predetermined brightness based onthe signals from the vehicle speed sensor 120 and the brightness sensor140 in switching on low beam. In this case, the switch ON/OFF controller100 realizes a light distribution pattern based on the town mode. Here,the town mode signifies a light distribution pattern suitable forrunning in an urban area having a high possibility that a walker walkson a sideway or the like.

Specifically, in the town mode, the switch ON/OFF controller 100 makesthe upper stage light source unit 20 stay to be switched OFF andswitches ON the other light source units 40, 70, 80 similar to the lowbeam light distribution constituting the base. At this occasion, theswitch ON/OFF controller 100 pivots the third and the fourth subunits 40a, 40 b of the middle stage light source unit 70 respectively in leftand right inverse directions by about 45°. Thereby, as shown by FIG. 17(b), the first region D1 which has been irradiated to a center is dividedinto two to respectively irradiate in left and right side directions.Thereby, light is positively irradiated road shoulders or the like topromote optical recognizability of a walker walking on, for example, theroad shoulder.

Further, in the town mode, as a way of producing other lightdistribution pattern, as shown by FIG. 17( c), the third and the fourthsubunits 40 a, 40 b of the middle stage light source unit 40 mayrespectively be pivoted only to, for example, the left side by an angleexceeding 20° to thereby diverge light to the road shoulder side by thediverging members 55. Also in this case, light is positively irradiatedto the road shoulder or the like to promote optical recognizability of awalker walking on, for example, the road shoulder.

Next, a motorway mode will be explained.

The switch ON/OFF controller 100 determines that the vehicle is runningon the automobile exclusive road when, for example, the vehicle runs bya predetermined speed or more based on the signal from the vehicle speedsensor 120 in switching on low beam. In this case, the switch ON/OFFcontroller 100 realizes a light distribution pattern based on themotorway mode. Here, the motor way mode signifies a light distributionpattern suitable for running on the automobile exclusive road where awalker is not present.

Specifically, in the motor way mode, the switch ON/OFF controller 100makes the upper stage light source unit 20 stay to be switched OFF andswitches ON the other light source units 40, 70, 80 similar to the lowbeam light distribution constituting the base. At this occasion, theswitch ON/OFF controller 100 angularly displaces all of the light sourceunits 20, 40, 60 in upper directions along with, for example, thesupport member 15 by operating the motor 18 for leveling (by 0.34°, by arange of about 0.1° through 0.5° as an example) (refer to FIG. 17( d)).Thereby, light at a vicinity of H line is intensified to promote remoteoptical recognizability.

Further, in the motor way mode, the switch ON/OFF controller 100 mayfurther increase the light amount to the front side by increasing thelight emitting amounts from the respective units 40, 70 by increasingpower supplied to the middle light source unit 40 and the fifth subunit70 for diverging in a long distance. At this occasion, it is preferableto reduce the light emitting amount from the sixth subunit by reducingpower supplied to the sixth subunit 80 for diverging in a shortdistance. Thereby, the light amount irradiated to the near front side ofthe vehicle is reduced, light irradiated to a vicinity of H line isrelatively emphasized to further promote long distance opticalrecognizability.

Next, the rain mode will be explained.

When the switch ON/OFF controller 100 determines that rain falls inrunning at, for example, a predetermined speed based on, for example,signals from the vehicle speed sensor 120 and the rain sensor 150 inswitching on low beam, the switch ON/OFF controller 100 realizes a lightdistribution pattern based on the rain mode. Here, the rain modesignifies a light distribution pattern with an object of promotingoptical recognizability under rainy weather.

Specifically, in the rain mode, the switch ON/OFF controller 100 makesthe upper stage light source unit 20 stay to be switched OFF andswitches ON the other light source units 40, 70, 80 similar to the lowbeam light distribution constituting the base. At this occasion, theswitch ON/OFF controller 100 angularly displaces all of the light sourceunits 20, 40, 60, in the upper directions along with, for example, thesupport member 15 by operating the motor 18 for leveling (by 0.34°, by arange of about 0.1° through 0.5° as an example). Thereby, light at avicinity of H line is intensified to promote remote opticalrecognizability.

Further, in the rain mode, the switch ON/OFF controller 100 may furtherincrease the light amount on the front side by increasing the lightemitting amounts from the respective units 40, 70 by increasing powersupplied to the middle stage light source unit 40 and the fifth subunit70 for diverging in a long distance. At this occasion, it is preferableto reduce the light emitting amount from the sixth subunit by reducingpower supplied to the sixth subunit 80 for diverging in a shortdistance. Thereby, the light amount irradiated to the near front side ofthe vehicle is reduced, light irradiated to a vicinity of H line isrelatively emphasized, and remote distance optical recognizability isfurther promoted. Further, although there is a case of deterioratingoptical recognizability by randomly reflecting light irradiated to thenear front side of the vehicle on a road face under rainy weather, lightreflected randomly can be restrained by reducing the light amount inthis way. Further, as an optional choice, as shown by FIG. 18( a), theremay be constructed a constitution of restraining random reflectionfurther positively by preventing the third region D3 from being formedby not switching the sixth subunit 80.

Further, in the rain mode, there may be constructed a constitution inwhich the switch ON/OFF controller 100 increases to supply power to alight source unit of the third subunit 40 a and the fourth subunit 40 bwhich is disposed on the right side in the direction of advancing thevehicle to thereby increase the light amount and pivots the light sourceunit in the left direction and increases light of a light source unit ofthe third subunit 40 a and the fourth subunit 40 b which is disposed onthe left side in the direction of advancing the vehicle. In this way, asshown by FIG. 18( b), the region of the first region D1 is shifted inthe left side direction and side optical recognizability cansimultaneously be promoted.

Further, in the rain mode, instead of constructing the constitution asshown by FIG. 18( b), there may be constructed a constitution in whichpower is increased to supply to the light source unit of the thirdsubunit 40 a and the fourth subunit 40 b which is disposed on the rightside in the direction of advancing the vehicle and pivots the lightsource unit by an angle exceeding 20° in the left direction to therebypositively diverge light in the left direction by the diverging member55 and only light of the light source unit of the third subunit 40 a andthe fourth subunit 40 b which is disposed on the left side in thedirection of advancing the vehicle is increased. In this case, as shownby FIG. 18( c), the region of the first region D1 is further shifted ina state of being diverged in the left side direction and side opticalrecognizability can further be promoted.

As has been explained above, the vehicle headlamp 10 of the embodimentincludes the upper stage light source unit 20, the middle stage lightsource unit 40, the lower stage light source unit 60 as a plurality oflight source units respectively including the light emitting portions asthe light sources, and optical members of the projecting lenses, thereflectors and the like for irradiating light from the light emittingportions along the optical axes. The upper stage light source unit 20,the middle stage light source unit 40, the lower stage light source unit60 are provided in the lamp body 14 constituting the lamp member by wayof the support member 15, and the low beam light distribution pattern isformed on the front side of the vehicle by overlapping light from therespective light source units 20, 40, 60. Here, the middle stage lightsource unit 40 constituting at least one of the plurality of lightsource units 20, 40, 60 is an optical axis variable light source unitsupported by the lamp body 14 to be able to change the optical axisindependently from the other optical light source units 20, 60.

Therefore, by pertinently changing the optical axis of the middle stageoptical unit 40 and changing an irradiating region, an optimum low beamlight distribution pattern can be formed in various situations. Further,in changing the low beam light distribution pattern, only four of thelight emitting portions are controlled at maximum and therefore, variouslight distribution patterns can be realized without increasing a numberof the light sources more than necessary. Further, it is not necessaryto install the light source unit including a number of the lightemitting portions and therefore, the vehicle headlamp can be downsized,a number of the light emitting portions can be made to be smaller thanthat in the background art and therefore, power consumption can berestrained.

As a specific constitution, the middle stage light source unit 40constituting the optical axis variable light source unit can form alight converging region including a skewed cutoff line in the low beamlight distribution pattern. According to the embodiment, a position ofirradiating the light converging region can pertinently be changed andtherefore, light can concentratedly be irradiated to a necessary portionin accordance with a situation, and the light distribution patterns inaccordance with various situations of the curve mode, the town mode, themotor way mode or the rain mode can be formed.

Further, the middle stage light source unit 40 constituting the opticalaxis light source unit changes a position of the light converging regionbetween the center of the front of the vehicle and the side of the frontside of the vehicle by moving the optical axis substantially in thehorizontal direction. By constituting in this way, light can beconcentrated on the center portion of the front side of the vehicle, orlight can be concentrated on the side portion on the front side of thevehicle as necessary. Further, in order to move the optical axis in thehorizontal direction, only the total of the light source unit 40(according to the embodiment, the third and the fourth subunits 40 a, 40b) may be pivoted and therefore, a complicated mechanism is not neededand a number of parts can be restrained from being increased more thannecessary.

Further, the middle light source unit 40 constituting the optical axisvariable light source unit is constituted by two of the third and thefourth subunits 40 a, 40 b.

Each of the third and the fourth subunits 40 a, 40 b can be constitutedas a light source of a directly emitted type including a projecting lens44 c as an optical member, arranged with a light emitting portion 42 cas a light source at a vicinity of a focal point of the projecting lens44 c for irradiating light directly from the light emitting portion 42 cto the font side. By constituting the light source unit of the directlyemitted type, a reflector can be omitted, or an installing space thereofcan be reduced. Further, when constituting the light source unit of thedirectly emitted type, light can easily be concentrated on an extremelynarrow region and therefore, the light source unit can preferably beused when light is intended to irradiate to pinpoint a certain narrowregion.

Further, as shown by FIGS. 4, 5(a) and 5(b), 12(a) to 12(d), and 13(a)to 13(d), the third and the fourth subunits 40 a, 40 b each can beconstituted as a light source unit of a reflecting type including thereflector 46 for reflecting light from the projecting lens 44 as theoptical member and the light emitting portion 42 c to a vicinity of thefocal point of the projecting lens 44 for irradiating light reflectedfrom the reflector 46 to the front side. When constituted as the lightsource unit of the reflecting type, the reflector is needed, some degreeof installing space needs to be ensured, however, by pertinentlydesigning the reflecting face 46 a of the reflector 46, light can easilybe controlled and therefore, light of a pertinent light amount caneasily be concentrated on a necessary region.

Further, according to the embodiment, each of the third and the fourthsubunits 40 a, 40 b of the middle stage light source unit 40constituting the optical axis variable light source unit is providedwith the diverging member 55 for diverging light emitted from the lightemitting portion 42 a between the projecting lens 44 and the lightemitting portion 42 a. The diverging member 55 is provided at a positionon which light is incident when the third and the fourth subunits 40 a,40 b are pivoted and the optical axis is moved from a position ofirradiating light to the center of the front side of the vehicle to theside of the front side of the vehicle and therefore, light is divergedby the diverging member 55 only in being pivoted.

Therefore, when light is irradiated to the center region which needs aclear cutoff line, the diverging member 55 does not hamper light frombeing propagated and when light is irradiated to the side region whichdoes not need so clear cutoff line, the irradiating region can bewidened by the pivoting angle or more. Therefore, the vehicle headlamphaving high side optical recognizability capable of irradiating lightover a wide side region can be constituted.

As the diverging member 55, the prism diverging lens in which the wallthickness along the direction of propagating light is thickened as beingremote from the optical axis can be used. By using the prism diverginglens, the irradiating region can be widened by the pivoting angle ormore and therefore, side optical recognizability of the vehicle can bepromoted.

Further, according to the embodiment, as the diverging member 55, thestep diverging lens formed with a plurality of steps can be used. Byusing the step diverging lens, the irradiating region can be widenedover on both left and right sides and therefore, light can be irradiatedevenly over the wide region and side optical recognizability of thevehicle can be promoted. Further, the prism diverging lens and the stepdiverging lens can be used selectively in accordance with a divergingpattern intended by a designer, and when other diverging pattern isintended to provide, other lens for diverging, or other kind of adiverging member may be used.

Further, according to the embodiment, the light source unit 60 in theplurality of the light source units 20, 40, 60 includes the cylindricallens 65 having the focal line extended in the horizontal direction, thefifth subunit (first subunit) 70 for making light incident on thecylindrical lens 65, and the sixth subunit (second subunit) 80. Thefifth subunit 70 is a directly emitted type subunit including the lightemitting portion 72 a (first light emitting element) for emitting lightto a vicinity of the focal line of the cylindrical lens 65 forirradiating light to the front side of the cylindrical lens 65. Further,the sixth subunit 80 is the reflecting type subunit including the lightemitting portion (second light emitting element) 82 a for emitting lightand the reflector 86 for reflecting light from the light emittingportion 82 a to a vicinity of the focal line of the cylindrical lens 65for irradiating light to the front side by way of the cylindrical lens65.

That is, according to the embodiment, the fifth subunit 70 and the sixthsubunit 80 commonly share the single cylindrical lens and therefore, incomparison with a case of providing respectively separate lenses, anumber of parts can be reduced and also spaces of attaching members of alens holder and the like can be made common and therefore, the fifthsubunit 70 and the sixth subunit 80 can be arranged to be proximate toeach other. Therefore, the lower stage light source unit 60 can bedownsized by reducing a space occupied by a total of the lower stagelight source unit 60.

Further, according to the embodiment, the light distribution region D3projected to the front side from the sixth subunit 80 by way of thecylindrical lens 65 is diverged in the vertical direction more than thelight distribution region D2 projected to the front side from the fifthsubunit 70 by way of the cylindrical lens 65. This is mainly derivedfrom a difference between the directly emitted type and the reflectingtype and various light distribution patterns can be realized even whenthe single cylindrical lens is used.

Further, according to the embodiment, the two light emitting portions 72a, 82 a are arranged on the same base member (board) 90. Therefore, inassembling, the two light emitting portions 72 a, 82 a may be positionedto the single base member 90 to be assembled with other member andtherefore, assembling performance can be promoted and accuracies ofpositioning the two light emitting portions can be promoted byconstituting a reference by the single base member 90.

Further, the light emitting portion 72 a is arranged at a vicinity ofthe focal line of the cylindrical lens 65 and above the focal line.Therefore, light projected to the front side by way of the cylindricallens 65 can be provided with a cutoff line, for example, a divergingregion constituting a portion of a horizontal line at a vicinity of Hline needing a clear brightness boundary can be formed.

Further, although according to the above-described explanation, thevehicle headlamp 10 has been explained as the vehicle headlamp which canbe used both for high beam and low beam, the invention is not limitedthereto but, for example, a vehicle headlamp exclusively for low beamcan also be constituted by constituting the vehicle headlamp 10 by, forexample, excluding the upper stage light source unit 20 and using onlythe middle stage light source unit 40 and the lower stage light sourceunit 60. Also in this case, principal operation and effect are the sameas those of the case in which the vehicle headlamp 10 can be used bothfor high beam and low beam.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the described exemplaryembodiments of the present invention without departing from the spiritor scope of the invention. Thus, it is intended that the presentinvention cover all modifications and variations of this inventionconsistent with the scope of the appended claims and their equivalents.

1. A vehicle headlamp comprising: a plurality of light source units; anda lamp member for supporting the plurality of light source units,wherein a low beam light distribution pattern is formed on a front sideof a vehicle by overlapping light from the respective light sourceunits; wherein one of the plurality of the light source units includes:a lens having a focal line extending in a horizontal direction, the lenssubstantially extending along a direction of the focal line; and firstand second subunits for irradiating light to the lens; the first subunitis a directly emitted type subunit including a first light emittingelement for emitting light from a vicinity of the focal line of the lensin a direction of the lens and irradiating light to the front side byway of the lens; and the second subunit is a reflecting type subunitincluding a second light emitting element for emitting light and areflector for reflecting light from the second light emitting element toa vicinity of the focal line of the lens and irradiating light to thefront side by way of the lens.
 2. The vehicle headlamp according toclaim 1, wherein a light distribution pattern projected from the secondsubunit to the front side by way of the lens is diverged in a verticaldirection more than a light distribution pattern projected from thefirst subunit to the front side by way of the lens.
 3. The vehicleheadlamp according to claim 1, wherein the first light emitting elementand the second light emitting element are arranged on the same board. 4.The vehicle headlamp according to claim 1, wherein the first lightemitting element is arranged at a vicinity of the focal line of the lensand above the focal line.
 5. The vehicle headlamp according to claim 1,wherein the light emitted by the first light emitting element isirradiated to the lens without being reflected.
 6. The vehicle headlampaccording to claim 5, wherein the lens is a cylindrical lens.
 7. Thevehicle headlamp according to claim 6, wherein the first light emittingelement includes a single light emitting face that faces toward thefront side.
 8. The vehicle headlamp according to claim 7, wherein thesecond light emitting element includes a single light emitting face thatfaces toward the reflector.
 9. The vehicle headlamp according to claim8, wherein the single face of the first light emitting element isperpendicular to the single face of the second light emitting element.10. The vehicle headlamp according to claim 7, wherein the single lightemitting face of the first light emitting element is the only lightemitting face of the first light emitting element.
 11. The vehicleheadlamp according to claim 8, wherein the single light emitting face ofthe second light emitting element is the only light emitting face of thesecond light emitting element.
 12. The vehicle headlamp according toclaim 1, wherein the second light emitting element is arranged at avicinity of the focal line of the lens and below the focal line.
 13. Thevehicle headlamp according to claim 1, wherein the first light emittingelement is disposed in the vicinity of the focal line of the lens, andthe second light emitting element is apart from the vicinity of thefocal line of the lens in a direction of an optical axis of theheadlamp.
 14. The vehicle headlamp according to claim 1, wherein thesecond subunit comprises a reflecting face having a vertical sectionalshape substantially in an elliptical shape with a first focal point at avicinity of the second light emitting element and a second focal pointat a vicinity of the focal line of the lens.